1. Field of the Invention
This invention relates to air conditioning units and more specifically to systems providing stored energy for use during periods of peak electrical demand.
2. Description of the Related Art
Reference is made to U.S. Pat. No. 4,735,064 issued to Harry Fischer and to U.S. Pat. No. 5,255,526 issued to Harry Fischer. Both of these patents utilize ice storage to shift air conditioning loads from on-peak to off-peak electric rates to provide economic justification. A need exists not only for load shifting from on-peak to off-peak periods, but also for increases in the capacity and efficiency of a given compressor so that the combination results in an overall increase in EER or energy efficiency ratio. This increase in overall efficiency is a governmental goal that controls the Public Service Commissions' relationship with the electric utility companies. The governmental goal of reducing energy usage greatly favors nighttime use of electricity for the following reason: First, low demand during nighttime hours allows electric utility companies to use their most efficient equipment. For example, high efficiency electric generators, typically stream-driven, produce a kilowatt-hour (KWH) for approximately 8900 BTU. In contrast, a peak hour high capacity electrical generator, such as a gas turbine, can use as much as 14,000 BTU to produce the same KWH of electricity. Second, for cooling systems, operating the system at night affords a higher efficiency by lowering the temperature of the condensing unit.